The present invention concerns a clip conveyor apparatus for conveying a clip line consisting of a plurality of clips in a clipping machine, in particular a sausage clipping machine.
In particular, the invention concerns a clip conveyor apparatus for conveying a closure clamp line or clip line consisting of a plurality of closure clamps or clips in a clipping machine, in particular a sausage clipping machine, where the clip conveyor apparatus has a drive unit and an advance or transport element. The advance element is coupled with its drive end to the drive unit. In that arrangement, it is drivable by the drive unit in such a way that its conveyor end that is in opposite relationship to the drive end describes an elliptical path and, for stepwise conveyance of the clip line, engages into intermediate spaces between two clips in the clip line and conveys the clip line stepwise in the advance direction.
It is known in practice that, for example, in the production of sausage products, the sausage meat is supplied to a clipping machine from a filling machine by way of a filling tube. In the clipping machine the filling material is introduced into a tubular packaging casing material that is closed at one end by a first clip at the first sausage end and is closed at the second sausage end by fitting a second clip. The packaging casing material of the sausage product produced in this way is then severed from the supply of the rest of the packaging casing material and the finished sausage product is discharged from the clipping machine.
For fitting and closing the closure clamps or the clip the clipping machine usually has a first closure tool, the die, and a second closure tool, the ram. They are arranged between the mouth opening of the filling tube and the transport device of the clipping machine for discharge of the finished sausage products. In that respect the die is usually disposed beneath the conveyor path of the sausage products and the ram is above that conveyor path. After a clip has been placed in the die and a gathered filling material-free plait portion of packaging casing material has been positioned in that clip, the two closure tools are moved towards each other to compress the clip disposed between them and thereby close the packaging casing material.
The clipping machine as described above is typically used to process clips that are made from a stamped aluminum wire line. For that purpose the clips are pre-bent in a U-shape and are joined together by means of legs which are bent over at a right angle at the ends of the limbs of the clips. The clip line formed in that way is fed to the die by a clip conveyor apparatus along a guide path which opens into the region of the associated closure tool.
In the transport or advance movement of a clip line by the clip conveyor apparatuses which are known in practice, the foremost clip, as is known, is fed to the die by an intermittently engaging advance element. As long as the foremost clip is still joined to the subsequent clip line, it is held thereby in the die in a stable condition. In the closure operation the die is firstly moved into its closure position or stroke end position. In that position the foremost clip is pressed against the plait portion of packaging casing material and is gripped between the plait portion and the die.
The ram moves towards the die in time-displaced relationship, that is to say while the die is still remaining in that position. Immediately prior to closure of the clip, the foremost clip is firstly severed from the subsequent clip line by means of a shearing device provided on the ram. At that moment the foremost clip is free and is only still pressed against the die by the tension in the plait portion. The clip is then plastically deformed by the ram further moving towards the die until the closure tools have moved towards each other, down to the height of the clip, and the clip is closed around the plait portion of the tubular casing material.
Such known clip conveyor apparatuses usually have a fixedly set advance stroke movement that is matched to the size of clip. If clips of a different size are to be processed, for example upon a change in the diameter of the sausage products, it is necessary to adapt the advance length or the advance stroke to the new clip size.
In that respect, it is also known in practice in relation to the known clip conveyor apparatuses to use an eccentric to produce the intermittent advance movement. That arrangement provides that a change in the advance stroke or the advance length can be achieved by displacement of the pivot point of the advance element. As the pivot point of the advance element on the die holder or die support is usually fixed, the latter has to be completely changed if a different size of clip is to be processed. This however requires the use of a tool and at least partial dismantling of the clipping machine. This is also time-consuming and thus cost-intensive.
The clip conveyor apparatuses known in practice suffer from a further disadvantage. The clip line is not stopped for a period of time between severing of the clip in the die and renewed engagement of the advance element into the following gap between two clips of the clip line, in the advance direction. If the clip line is subjected to a tensile stress due to the advance movement, it can be pulled back upon separation of the foremost clip from the clip line in the engagement region of the advance element, in opposite relationship to the advance direction, and that impedes or prevents a desired engagement.